Climatic controls of the middle marsh zone in the Bay of Fundy

The ecological importance of Plantago maritima within a salt marsh on the Bay of Fundy is documented through measurements of cover, density, and biomass. During late August 1993, peak standing crops of Plantago were as high as 532 g m(-2), and composed as much as 96% of the biomass of a stand of vegetation. Plantago is a dominant component of the marsh vegetation at an elevation just above the Spartina alterniflora-dominated low marsh, and is found as a dominant when growing in association with a number of plant species characteristic of the high marsh. We hypothesize that the existence of this community is dependent upon regular ice-shearing of Spartina patens, which would otherwise competitively exclude Plantago. This hypothesis is supported by the elevational limits of Plantago dominance and the geographical Limitation of Plantago communities to portions of the northwestern Atlantic subjected to winter temperatures which average below 0 degrees C.